Graphics Programs Reference
4. On the screen, you see small, yellow squares where segments meet.
Hover over one of them; after a moment, the icons for the Coincidence
constraints appear. There are two, to denote that two elements are
affected by the constraint. Move your mouse back and forth between
the two, and you'll see that the different lines highlight.
5. Position your mouse over the Perpendicular icon at lower left. Both
segments highlight simultaneously.
6. If you used the same settings for your Application Options as I have,
from the exercise in Chapter 1, you see an additional icon in the
center of the screen: This is for the projected center of the sketch.
Right-click the icon, and select Hide to turn off the icon's visibility.
7. Right-click the Perpendicular icon at upper left. Select the Delete
option from the context menu that appears on the screen. Doing this
not only removes the icon but also eliminates the relationship
between the entities.
8. Click and drag the right endpoint of the top horizontal line, and see
that it moves. Release the mouse button; the sketch remains as it was
previewed, as shown in Figure 2.10.
9. Press the F9 key to turn off the display of the sketch constraints.
You can display another tool temporarily on the screen to better understand
the state of the sketch constraints: The Degrees of Freedom (DOF) of the sketch
shows which elements are still fl exible in their movement and how. You'll use
this powerful yet simple addition in the next exercise to make the effects of
sketch dimensions easier to understand.
Sketch constraints create specifi c relationships between parts of the geometry.
When you need to be able to defi ne a relationship based on a size, that's when
you need a sketch dimension .
Sketch dimensions have slightly fewer options than the dimensions you place
on drawing views but follow the same basic rules. Unlike many 2D CAD tools,
only one Dimension tool is used for defi ning a sketch in Inventor. You can use
this Dimension tool to place different types of dimension simply by gesturing on
the geometry that you want to control. You also have some context-menu options;
but for the most part, picking the sketch elements will do the trick.